Drilling apparatus

ABSTRACT

The invention provides a drilling apparatus ( 1 ) having a base ( 2 ) from which a drilling arm is pivotally mounted. The drilling arm ( 3 ) has an inner arm ( 4 ) and an outer arm ( 5 ). The inner arm ( 4 ) has a first end ( 6 ) and a second end ( 7 ). The first end ( 6 ) is pivotally connected via a first pivot joint ( 8 ) to the base ( 2 ). The outer arm ( 5 ) has a first end ( 9 ) and a second end ( 10 ). The second end ( 7 ) of the inner arm ( 4 ) is pivotally connected via a second pivot joint ( 11 ) to the first end ( 9 ) of the outer arm ( 5 ). At the second end ( 10 ) of the outer arm ( 5 ) is a drill mounting assembly ( 12 ). Actuation of the inner and outer arms ( 4 ) and ( 5 ) is achieved via drive means in the form of hydraulic cylinders ( 13 ). Proper operation of the cylinders ( 13 ) causes the second end ( 10 ) of the outer arm ( 5 ) to follow a substantially linear path.

FIELD OF THE INVENTION

This invention relates to improvements in or relating to drillingapparatus. More specifically, but not exclusively, the invention relatesto improvements in such apparatus used in demanding environments such asthe mining, tunnelling and water bore drilling industries.

BACKGROUND

An area of significant application of drilling apparatus in both themining and tunnelling industries is in drilling holes for rock-bolting.Rock-bolting is undertaken to prevent rock falls and cave-ins, and tootherwise stabilise the tunnel or mine roof and walls.

In the mining or quarrying industries drilling apparatus are also usedas part of the excavation process, for example, with holes being drilledto set explosives for blasting. Other uses include drilling smalldiameter holes for purposes such as stoping, and probe drilling.

Prior art drilling apparatus for use in the aforementioned situationsnormally includes a boom along which a percussion hammer drill slides.The boom is typically mounted longitudinally in a cradle with the drillslidably mounted on the boom. A separate feeding mechanism is providedfor displacing each of the boom and the drill. In such apparatus thedrill is typically moved by means of a chain or rope which goes aroundwheels mounted at the ends of the boom and the ends of which arefastened to the drill. The chain is moved by actuation of a hydrauliccylinder or the like. The boom, in turn, is moved with respect to thecradle by means of a hydraulic cylinder mounted between it and thecradle.

A factor relevant to the design of drilling equipment used inunderground mining and tunnelling is the issue of size andmanoeuvrability in a confined space.

In prior art apparatus, if a 6 m hole is required to be drilled, theboom must also be 6 m long. Such a configuration is able to drillshorter holes, however, when a shorter hole is required a 6 m boom witha 2 m drill steel has 4 m of wasted boom behind the drill.

Drilling rigs attached to wheeled vehicles are often required tomanoeuvre around very tight corners in underground tunnels. The lengthof the drilling apparatus often hinders its manoeuvrability, andcollisions are frequent. Disassembly, in order to improvemanoeuvrability is generally impractical.

In addition to space considerations, the drilling apparatus used inmining, tunnelling and quarrying must be of robust and rugged design tocope with other aspects of the harsh environment.

Unfortunately the sliding arrangements of prior art drilling apparatusdo not fully address this requirement, and have high maintenance needs.Usually the greatest damage occurs to exposed hydraulic hosing supplyingthe driving force to the hydraulic cylinders generating forward movementof the boom, and to the drill. Another problem area is the exposedhydraulic hose reeler. These are at constant risk of damage due tofalling rocks or from being crushed by any number of the moving parts.

In addition to rock fall damage, excessive wear and tear is generated bythe extreme working environment. The sliding system used to advance thedrill steel into the rock is poorly suited to a situation where finerock chips from flushing water are constantly washed over and betweenthe wearing surfaces. Where a percussion drill is employed, thissituation is compounded by the hammer action which generates significantcomponent vibration causing acceleration of wear between moving parts.These prior art systems also have various other significant wearingparts involved in the act of moving the drill forward which aresubjected to similar wear patterns.

The sliding configuration of the prior art apparatus also hinders otheractivities commonly engaged in as part of the tunnelling or miningprocess, such as, for example, the application of shot-crete. Shot-creteis an extremely abrasive material, containing steel fibres suspended inconcrete. This is sprayed onto the tunnel interior for roofstabilisation purposes. If shot-crete is accidentally sprayed onto thesliding surfaces of the prior art apparatus wear is accelerated, andrepair costs are increased.

Another recognised area of application of the invention, primarilybecause of the compact nature of apparatus constructed according to theinvention, is use in conjunction with bore drilling rigs which can needto be transported from one site to another on public roads and highways.

Existing configurations typically employ a tower design to drillsubstantially vertically downwards. Such arrangements are cumbersome andcan often require considerable set up time after transport to the drillsite. Further, because of the general configuration of such equipment,transportation in itself is an issue. Even partially disassembled, themovement of such equipment on public roads means heavy transportvehicles are required, the transport operation is time consuming andcostly. Public inconvenience also often becomes an issue.

It is an object of the invention to provide drilling apparatus whichovercomes at least some of the above identified problems with prior artapparatus, or which at least provides the public with a useful choice.

SUMMARY OF THE INVENTION

In its broadest aspect the invention provides a drilling apparatushaving a base to which a drill mounting arm is pivotally connected, saiddrill mounting arm comprising an inner arm and an outer arm, said innerarm having a first end and a second end and said outer arm having apivot joint end and a free end, said first end of the inner arm beingpivotally connected via a first pivot joint to the base and said secondend being pivotally connected via a second pivot joint to the pivotjoint end of the outer arm, a mounting means adapted to in use mount adrill being provided at the free end of the outer arm, the apparatusfurther including drive means adapted to drive the mounting means at thefree end of the outer arm along a substantially linear path.

Preferably the inner arm is offset from the outer arm to allow the outerarm to rotate past the inner arm without interference. Optimally theouter arm can rotate at least 320 degrees relative to the inner arm.

Preferably the inner arm can rotate 180 degrees relative to the base.

Desirably the inner arm and the outer arm are substantially the samelength, and the base is configured and arranged to avoid interferingwith the free end of the outer arm.

Conveniently the mounting means is pivotally mounted via a third pivotjoint to the free end of the outer arm.

Preferably the drive means comprises one or more hydraulic cylinders.Optimally the one or more hydraulic cylinders drive pivoting of thefirst, second and third pivot joints.

Desirably the second pivot joint includes an offset arm on the same axisas the outer arm but offset by 90 degrees to the outer arm, actuation ofthe second pivot joint being achieved via a pair of said hydrauliccylinders mounted such that when the first said hydraulic cylinder isfully extended or retracted, and therefore has no ability to rotate theouter arm, the second said hydraulic cylinder is in the middle of itsstroke.

In a more preferred form the invention the third pivot joint serves as adrill angle correction joint so as to, in use, keep a drill steel on thecorrect plane during the drilling process.

Preferably the apparatus further includes a drill steel support arm to,in use, support the drill steel in the correct position during drilling.

Desirably the said support arm is retractable, with retraction oradvancement of the support arm being parallel to the drilling axis.

Conveniently all hydraulic hosing associated with the drive means ishoused within the inner and outer arms. Optimally in order to enablehydraulic fluid, water and air to reach the various hydraulic equipmentand a drill in use mounted on the mounting means rotary seals and portedpins are employed in the joints and are configured and arranged to allow360 degree rotation without twisting hoses.

Desirably the mounting means includes a shot-crete nozzle and theapparatus includes shot-crete feed pipes to enable, in use, shot-creteto be sprayed using the drilling apparatus.

Optimally the apparatus further includes computerised controls such thatthe various hydraulic control and positioning cylinders are actuatedaccording to a pattern controlled by computer software.

Desirably the computerised controls include sensors to establish thepositions of the various component parts of the apparatus and suchcomputerised controls include self-diagnostic features so that when theinner and outer arms are in a certain physical position the sensors arechecked for accuracy.

Conveniently a sensor is provided on the hydraulic fluid feed circuit tosense if the drill steel is starting to become jammed.

Preferably the apparatus includes a sensor on the hydraulic fluid feedcircuit supplying rotation to the drill steel, said sensor being adaptedto sense the frequency of the hammer action for determining the optimumfeed speed/pressure settings.

Desirably the invention further includes electronic data storage anddisplay means for data recorded from various sensors on the hydraulicand pneumatic feeds to establish tool and drill steel consumption andefficiency, rock hardness and geology and the number of bolts installedin a given period of use.

Advantages of the present invention are that it provides a feed devicefor rock drilling in which the structure carrying out the displacingmovements is as simple as possible and utilises no sliding mechanism orexposed hoses.

A further advantage is that the apparatus according to the invention isable to multitask, being able to be used in such applications asspraying shot-crete, as well as a rock-bolt and probe drill.

A yet further advantage is that apparatus according to the invention canutilise a range of different drill steel lengths in the sameconfiguration without wasting space.

A still further advantage is that the inventive apparatus can be easilyfolded into a compact form for transport purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

Two preferred forms of the invention will now be described, by way ofexample only, and without limitation as to the intended scope of theinvention as claimed.

The preferred embodiments have particular application in rock drilling,and are described below with reference to the accompanying drawings. Thedrawings comprise FIGS. 1 to 19 as follows:

FIG. 1: is a side elevation of a drilling apparatus according to thepresent invention;

FIG. 2: is a plan view of the apparatus of FIG. 1;

FIG. 3: is an rear view of the apparatus of FIG. 1;

FIG. 4: is a front view of the apparatus of FIG. 1;

FIG. 5: is a schematic side elevation of the apparatus of FIGS. 1 to 4in use showing the various hydraulic cylinders and pin joint linkages;

FIG. 6: is a schematic side elevation of an alternative, substantiallymechanically actuated version, of a apparatus according to theinvention;

FIGS. 7 & 8: are three dimensional schematic views of the apparatus ofFIG. 6 in different states of actuation;

FIGS. 9 to 12: are a series of three dimensional views of the apparatusof FIGS. 1 to 4 at different stages of actuation, demonstrating therange of motion possible;

FIGS. 13 to 18: are a series of side elevations of the apparatus ofFIGS. 1 to 4 at various stages of actuation during the drilling process;

FIG. 19: is a perspective view of the apparatus of FIGS. 1 to 4 foldedfor purposes such as transport;

FIG. 20: is a perspective view of the apparatus of FIGS. 1 to 4 as seenfrom the rear right-hand side; and

FIG. 21: is a perspective view of the apparatus of FIG. 20 as seen fromthe front left-hand side.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, a drilling apparatus as generally indicatedat 1 is provided. The apparatus 1 has a base 2 from which a drilling arm3 is pivotally mounted. The drilling arm 3 has an inner arm 4 and anouter arm 5.

The inner arm 4 has a first end 6 and a second end 7. The first end 6 ispivotally connected via a first pivot joint 8 to the base 2. The outerarm 5 has a first end 9 and a second end 10. The second end 7 of theinner arm 4 is pivotally connected via a second pivot joint 11 to thefirst end 9 of the outer arm 5.

At the second end 10 of the outer arm 5 is a drill mounting assembly 12.

Actuation of the inner and outer arms 4 and 5 is achieved via drivemeans in the form of hydraulic cylinders 13. Proper operation of thecylinders 13 causes the second end 10 of the outer arm 5 to follow asubstantially linear path.

The inner arm 4 is offset from the outer arm 5 to allow the outer arm 5to rotate past the inner arm 4 without interference. The offset is suchthat the outer arm 5 can rotate at least 320 degrees relative to theinner arm 4.

The function of the first pivot joint 8 is to maintain the drill arm 3at the correct angle during the drilling process. In the preferredembodiment illustrated in FIGS. 1 to 5 and 9 to 22 (hereafter “the firstpreferred embodiment”) this is achieved using two hydraulic cylinders101 and 102 for positioning. These cylinders 101 and 102 are offset by75 degrees to each other. The reason for this is to have at least one ofthe cylinders 101/102 normal to the base joint 8 pivot axis at any giventime and thus enable the inner arm 4 to rotate up to 180 degreesrelative to the base 2.

In the first preferred embodiment hydraulic cylinders 103 and 104manipulate the arms 4 and 5 relative to one another. The pivot joint 11utilises an arrangement that enables the outer arm 5 to rotate more than180 degrees.

In that regard, an offset lever 105, on the same axis as the outer arm5, but having the hydraulic cylinder 103 driving position offset by 90degrees to the cylinder 104 driving position of the outer arm 5 isprovided. This means that when one cylinder 103/104 is fully extended orretracted, and therefore has no ability to rotate the arm, the othercylinder 104/103 is in the middle of its stroke. Thus when the offsetarm cylinder 103 is fully retracted and cannot rotate the offset lever105 the outer arm cylinder 104 is in the middle of its stroke and normalto the axis.

The inner arm 4 and the outer arm 5 are substantially the same length,and the arrangement of joints 8, 11 and arms 4, 5 is such that thedrilling process is able to start from behind the base joint 8, and alsomeans the arm 4, 5 lengths only need to be in the order of 28% of thedrill steel length. For example, when using a 4 m drill steel each ofthe inner and outer arms 4, 5 need only be approximately 1.2 m long.This attribute therefore provides maximum flexibility as the range ofdrill steel lengths that can be used.

Mounted at the free end 10 of the outer arm 5 is a drill anglecorrection joint 14. The function of this joint 14 is to keep the drillon the correct plane during the drilling process. The mechanism used isknown, being a mechanical assembly similar to that used to movehydraulic excavator buckets. This system includes a drill cradle 15 anda drill cradle positioning cylinder 106 move the drill cradle 15 up to180 degrees.

The first preferred embodiment of the invention further includes a drillsteel positioning arm 107. Attached to the forward end of this arm 107is the drill steel guide block 108. The arm 107 has three functions,namely, it targets the head 201 of the drill steel 202, it holds thedrill steel 202 in position for collaring the hole, and it moves to themiddle of the drill steel 202 as a support when the drill 203 isworking.

The arm 107 is retractable, with the direction retraction or advancementbeing linear and parallel to the drilling axis. The arm 107 is pivotallymounted to the base 2, with rotation being actuated by a hydrauliccylinder 109 extending between the arm 107 and the base 2.

Stability for the drill steel 202 when collaring is not given by therigidity of the arm 107 but rather, by the point 204 at the free end ofthe arm 107 pushing into the rock. This force is achieved by applying anextending force to the arm 107, preferably resulting in an applied forceof up to 8 tonnes.

FIG. 5 shows schematically the operation and actuation points of thevarious hydraulic cylinders, linkages and pivot joints.

In the first preferred embodiment all hydraulic hosing associated withthe various hydraulic equipment is housed within the inner and outerarms 4, 5 (not shown in FIG. 5). This is a significant advantage overprior art designs.

In order to enable hydraulic fluid, water and air to reach the varioushydraulic equipment, hammer and drill 203 rotary seals and ported pinsare employed in the joints and are configured and arranged to allow 360degree rotation without twisting hoses.

In the first preferred embodiment the apparatus 1 further includescomputerised controls such that the various hydraulic control andpositioning cylinders are actuated according to a pattern controlled bycomputer software.

Computer control also allows a multitude of different drill steellengths 202 to be used with the same sized unit 1. The desired drillsteel length 202 can simply be selected from the computer's menu and thecomputer then recalculates the mechanical movement to suit the drillsteel length 202.

In the first preferred embodiment the linear movement of the arm 3 (usedwhile drilling or positioning) is achieved using computer control. Thereare a number of elements to this control strategy. Firstly, the arm 3and joint 8, 11, 14 positions are measured with sensors 301, 302, 303and 304. These sensors are rugged devices immune to vibration, and areused to measure rotational position and velocity.

The Cartesian coordinates of the arm 107 are calculated using themeasured sensor positions.

The desired angular position of the arms 4, 5 are then calculated usingthe Cartesian coordinates of the arm 107. The desired angular velocitiesare also calculated. This is done by differentiating the desired arm 4,5 angular positions.

The desired arm joint 8, 11 velocities and arm 4, 5 positions are usedto calculate desired hydraulic cylinder velocities, which are achievedthrough PID controllers via pulse width modulation (PWM) amplifiersdriving proportional hydraulic valves.

The process variables for the PID controllers are the arm joint 8/11/14positions. The feedback of arm joint positions are measured with sensors301, 302 and 303.

The linear movement of the arms 4, 5 while drilling is similar in mostrespects to positioning. However, the arms 4, 5 and drill cradle 15follow an imaginary line through the drill steel guide block 108, at thesame shooting angle as the arm 107 into the rock.

During drilling the arm 107 extends at half the rate of the drill steel202.

Before the start of drilling the arm 107 leads the arms 4, 5 and thedrill cradle 15. The operator adjusts the angle of the arm 107 and itsextension until contact is made with the rock.

As illustrated in FIGS. 9 through 18, the drilling process begins withcollaring. This is the same as the drilling process described withexception that the position of the arm 107 remains fixed during theprocess.

While drilling the hydraulic feed pressure is used to adjust the targetvelocity of the drill steel 202. Feed pressure is measured by a drillingload sensor 305 mounted between the drill 203 and the drill cradle 15.

Once the required drilling depth has been reached the drill steel 202 isautomatically retracted. Retraction is essentially similar to drillingexcept that instead of the drill steel 202 following the line into therock it follows the line in the opposite direction and the arm 107remains fixed throughout the process.

A self-diagnostic feature forms part of the computer control system. Inthat regard, the hydraulic proportional control valves requirecalibration data so the computer is able to control cylinder velocitiesaccurately. The computer moves each joint 8, 11, 14 over a range ofPulse Width Modulations (PWM) while measuring the velocity for eachjoint. From this the cylinder velocities are calculated. Thismodulation/cylinder velocity data is stored and used for positioning anddrilling operations.

Because of the mechanical and electrical nature of the control systemsof the first preferred embodiment, it lends itself well to data storageand display such as tool and drill steel consumption and efficiency,rock hardness and geology, and simple information like the number ofbolts installed in one shift. Presently available rock bolting systemsare fully mechanical and offer no means of recording rock geology orother important data.

The first preferred embodiment thus can further include a geo-detectionsystem to record rock geology through the use of pressure sensors on thedrill hammer. Desirably this information is sent to a touch screencontrol panel (TSCP) or the like and is then translated to a 3D image ofthe tunnel in which holes bored by the drill unit can be displayed. Thisallows project geologists to view the rock conditions in real-time. Theholes may be colour-coded to indicate varying hardness of the rock.

Referring now specifically to FIGS. 6 to 8, a wholly mechanical versionof apparatus 1 is shown.

In this second preferred embodiment there is no computerised control. Itis purely a mechanical design incorporating hydraulic cylinders andmechanical linkages. However, the operating principles are fundamentallythe same as in the first preferred embodiment, and like components arelike numbered.

As illustrated, there are two side by side arms 3, with the two innerarms 4 spaced apart to allow the outer arm pair 5 to swing throughbetween them.

The cylinder linkages 401 rotate the inner arms 4 anti-clockwise whenthe hydraulic cylinders 13 are retracted. During the first half of thestroke, the outer arms 5 are pulled forward by reaction arms 402 (whichare in tension). During the second half of the stroke, the outer arms 5are pushed forward by the reaction arms 402 (the reaction arms are incompression), which are connected to the lever arms 403. The lever arms403 are rotated via the cylinder linkages 401 when the cylinders 13 areretracted, thus causing the outer arms 5 to rotate in a clockwisedirection.

The rock drill attitude is maintained via the two drill leveling arms404.

While the hydraulics of the first preferred embodiment has beendescribed as computer controlled, in an alternative approach control canbe achieved by utilizing flow dividers and differing sized cylinders tomaintain a linear path at the end of the arm 5. In such an embodimentthe outer arm 5 connection joint 11 to the inner arm 4 travels twice therotational distance of the inner arm joint 8 connection. To achieve thisratio a flow divider is employed so that the volume of the cylindersused to manipulate the outer arm 5 are half the volume of cylinders usedfor the inner arm 4.

Another method of achieving this is to use slave cylinders between theinner arm 4 and the base 2. These must be twice the volume of thecylinders used to manipulate the outer arm 5.

Turning now to use of the first preferred embodiment in the context of abore rig arrangement, the apparatus 1 can be mounted onto the bed of atruck or the like transport unit (not shown). The component parts of theapparatus 1 are substantially as described above, however, the drill 203is replaced with an appropriate boring head of known configuration.

Referring specifically to FIG. 19, the base 2 can, for example, bepivotally mounted to the vehicle bed via mounts 501 and 502. In theorientation illustrated the apparatus 1 is at its most compact andideally suited to transport. In use the base 2 may be pivoted viahydraulic cylinders at an angle of, for example, 90 degrees so that thearm 107 is directed vertically for the purposes of commencing the boringoperation. Known vehicle stabilizers and the like may be employed toprovide a stable boring platform.

Advantages of the present invention are thus that rock drillingapparatus utilising the technology of the invention provide a drillingarm that has few wearing parts, no exposed hydraulic hosing, andconsequently much reduced maintenance, resulting in reduced costly andinconvenient down time. Further, its design configuration allows use ofthe apparatus in restricted spaces, unlike conventional devices.

It will be appreciated without inventive adaptation the apparatus of thepresent invention can be modified for spraying shot-crete as a tunnellining. In such a set up the same basic mechanical design would be usedbut a shot-crete nozzle would work in conjunction with the drill toenable one rig to perform two tasks. The computerised control formovement would be modified to suit this further application.

Where in the foregoing description reference has been made to integersor components having known equivalents then such equivalents are hereinincorporated as if individually set forth.

Although this invention has been described by a way of example usingpossible embodiments, it is to be appreciated that improvements and/ormodifications may be made thereto without departing from the scope ofthe invention as claimed.

1. A drilling apparatus having a base to which a drill mounting arm ispivotally connected, said drill mounting arm comprising an inner arm andan outer arm, said inner arm having a first end and a second end andsaid outer arm having a pivot joint end and a free end, said first endof the inner arm being pivotally connected via a first pivot joint tothe base and said second end being pivotally connected via a secondpivot joint to the pivot joint end of the outer arm, a mounting meansadapted to in use mount a drill being provided at the free end of theouter arm, the apparatus further including drive means adapted to drivethe mounting means at the free end of the outer arm along asubstantially linear path.
 2. An apparatus according to claim 1 whereinthe inner arm is offset from the outer arm to allow the outer arm torotate past the inner arm without interference.
 3. An apparatusaccording to claim 2 wherein the outer arm can rotate at least 320degrees relative to the inner arm.
 4. An apparatus according to claim 1wherein the inner arm can rotate 180 degrees relative to the base.
 5. Anapparatus according to claim 1 wherein the inner arm and the outer armare substantially the same length, and the base is configured andarranged to avoid interfering with the free end of the outer arm.
 6. Anapparatus according to claim 1 wherein the mounting means is pivotallymounted via a third pivot joint to the free end of the outer arm.
 7. Anapparatus according to claim 1 wherein the drive means comprises one ormore hydraulic cylinders.
 8. An apparatus according to claim 7 whereinthe one or more hydraulic cylinders drive pivoting of the first, secondand third pivot joints.
 9. An apparatus according to claim 8 wherein thesecond pivot joint includes an offset arm on the same axis as the outerarm but offset by 90 degrees to the outer arm, actuation of the secondpivot joint being achieved via a pair of said hydraulic cylindersmounted such that when the first said hydraulic cylinder is fullyextended or retracted, and therefore has no ability to rotate the outerarm, the second said hydraulic cylinder is in the middle of its stroke.10. An apparatus according to claim 6 wherein the third pivot jointsserves as a drill angle correction joint so as to, in use, keep a drillsteel on the correct plane during the drilling process.
 11. An apparatusaccording to claim 10 wherein the apparatus further includes a drillsteel support arm to, in use, support a drill steel in the correctposition during drilling.
 12. An apparatus according to claim 11 whereinthe said support arm is retractable, with retraction or advancement ofthe support arm being parallel to the drilling axis.
 13. An apparatusaccording to claim 9 wherein all hydraulic hosing associated with thedrive means is housed within the inner and outer arms.
 14. An apparatusaccording to claim 13 further including a drill mounted on the mountingmeans.
 15. An apparatus according to claim 14 wherein in order to enablehydraulic fluid, water and air to reach the various hydraulic equipmentand the drill mounted on the mounting means rotary seals and ported pinsare employed in the joints and are configured and arranged to allow 360degree rotation without twisting hoses.
 16. An apparatus according toclaim 13 wherein the mounting means includes a shot-crete nozzle and theapparatus includes shot-crete feed pipes to enable, in use, shot-creteto be sprayed using the drilling apparatus.
 17. An apparatus accordingto claim 6 wherein the apparatus further includes computerised controlssuch that the various hydraulic control and positioning cylinders areactuated according to a pattern controlled by computer software.
 18. Anapparatus according to claim 17 wherein the computerised controlsinclude sensors to establish the positions of the various componentparts of the apparatus and such computerised controls includeself-diagnostic features so that when the inner and outer arms are in acertain physical position the sensors are checked for accuracy.
 19. Anapparatus according to claim 18 wherein a sensor is provided on thehydraulic fluid feed circuit to sense if the drill steel is starting tobecome jammed.
 20. An apparatus according to claim 18 wherein theapparatus includes a sensor on return feed of the hydraulic fluid feedcircuit supplying rotation to the drill steel, said sensor being adaptedto sense the frequency of the hammer action for determining the optimumfeed speed/pressure settings.
 21. An apparatus according to claim 18wherein the apparatus further includes electronic data storage anddisplay means for data recorded from various sensors on the hydraulicand pneumatic feeds to establish tool and drill steel consumption andefficiency, rock hardness and geology and the number of bolts installedin a given period of use.
 22. (canceled)
 23. An apparatus according toclaim 19 wherein the wherein the apparatus includes a sensor on returnfeed of the hydraulic fluid feed circuit supplying rotation to the drillsteel, said sensor being adapted to sense the frequency of the hammeraction for determining the optimum feed speed/pressure settings.